How long to image the Owl Nebula with the ZWO Seestar S50
From a Bortle 6 suburban sky, the ZWO Seestar S50 needs about 38 min (228 subs of 10 s with the built-in dual-band (LP filter) filter) for a solid image of the Owl Nebula. A quick look takes 9 min; a showpiece 2 h 32 min. Under a Bortle 3 rural sky the solid figure drops to 29 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 8% of the frame’s short side.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 7 min42 subs | 28 min167 subs | 1 h 51 min668 subs |
| Bortle 2Typical dark site | 7 min43 subs | 28 min169 subs | 1 h 52 min675 subs |
| Bortle 3Rural | 7 min44 subs | 29 min173 subs | 1 h 55 min689 subs |
| Bortle 4Rural / suburban transition | 8 min46 subs | 30 min181 subs | 2 h723 subs |
| Bortle 5Suburban | 8 min49 subs | 32 min195 subs | 2 h 09 min777 subs |
| Bortle 6Bright suburban | 9 min57 subs | 38 min228 subs | 2 h 32 min910 subs |
| Bortle 7Suburban / urban transition | 12 min73 subs | 48 min291 subs | 3 h 14 min1,164 subs |
| Bortle 8City | 16 min98 subs | 1 h 05 min390 subs | 4 h 19 min1,557 subs |
| Bortle 9Inner city | 25 min150 subs | 1 h 40 min599 subs | 6 h 39 min2,395 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 49 min of run time. The Seestar S50’s battery (rated about 6 h) should cover it; a power bank still keeps the phone running the app alive. (Bortle 6, solid image; we allow 30% over the integration time.)
- USB-C power bank 20000mAh 5V 3AThe S50 draws 5 V 3 A over USB-C and runs while charging; no PD needed.
- Seestar S50 dew shieldThe built-in heater copes with most nights; a shield helps in heavy dew and blocks stray light.
- red LED head torchRed light keeps your night vision; white light costs you twenty minutes of dark adaptation every time.
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How it frames
The Owl Nebula is 3.4′ × 3.3′ across. The Seestar S50 frames 1.28° × 0.72° at 2.39″ per pixel, so it fills 8% of the frame’s short side.
Longer subs
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode (app 2.5 and later). Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 10 s | 29 min173 subs | 32 min195 subs | 48 min291 subs |
| 20 s | 23 min69 subs | 27 min80 subs | 43 min129 subs |
| 30 s | 21 min43 subs | 25 min50 subs | 41 min82 subs |
| 60 s | 30 min30 subs | 30 min30 subs | 39 min39 subs |
With and without the dual-band filter
| Filter | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| UV/IR-cut (no light-pollution filter) | 23 min141 subs | 35 min213 subs | 1 h 28 min529 subs |
| dual-band (LP filter) | 29 min173 subs | 32 min195 subs | 48 min291 subs |
About the Owl Nebula
A round planetary with two dark eyes. Large for its class and low in surface brightness; dual-band helps a lot.
M97, NGC 3587 · Planetary nebula in Ursa Major · magnitude 9.9 · 3.4′ × 3.3′ · best in Feb, Mar, Apr. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Planetary nebulae are small but intensely bright per pixel in OIII and H-alpha, so they respond very well to a dual-band filter and do not need much time for the main shell. The faint outer halos most of them have are a different proposition and need hours. Keep subs short if the central region saturates.
About the ZWO Seestar S50
The scope that made smart astrophotography mainstream. 50 mm triplet, 2 MP sensor, dual-band filter on a wheel. Alt-Az stacking at 10 s, EQ mode unlocks 60 s. Out of production since 2026 and replaced by the S50 Pro, but there are a great many in use.
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode (app 2.5 and later). Built-in dual-band light-pollution filter, switchable in the app.
Longer subs matter most under dark skies, where read noise rather than skyglow sets the floor. From a city the difference between 10 s and 60 s subs is small; from a rural site it can halve the total time, especially with a dual-band filter in place.
Stack across nights. Every smart scope app can continue a stack or you can combine the saved frames on a computer; the figures here are totals, not single-session limits.
Have an image of the Owl Nebula from a Seestar S50? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Owl Nebula with the ZWO Seestar S50 Pro: 42 min from Bortle 6
- Owl Nebula with the ZWO Seestar S30: 43 min from Bortle 6
- Owl Nebula with the ZWO Seestar S30 Pro: 45 min from Bortle 6
- Owl Nebula with the DwarfLab DWARF 3: 49 min from Bortle 6
- Owl Nebula with the DwarfLab DWARF mini: 37 min from Bortle 6
- Owl Nebula with the DwarfLab Draco: 30 min from Bortle 6
- Owl Nebula with the DwarfLab DWARF II: 3 h from Bortle 6
- Owl Nebula with the Vaonis Vespera II: 54 min from Bortle 6
- Owl Nebula with the Vaonis Vespera Pro: 1 h 59 min from Bortle 6
- Owl Nebula with the Vaonis Vespera 3: 51 min from Bortle 6
- Owl Nebula with the Vaonis Vespera Pro 2: 1 h 54 min from Bortle 6
- Owl Nebula with the Unistellar eQuinox 2: 47 min from Bortle 6
- Owl Nebula with the Unistellar Odyssey: 3 h 36 min from Bortle 6
- Owl Nebula with the Celestron Origin: 14 min from Bortle 6
- Owl Nebula with the Celestron Origin Mark II: 20 min from Bortle 6
All telescopes for the Owl Nebula · All targets for the Seestar S50